Apparatus for observing vocal cord wave

ABSTRACT

1,051,421. Cathode-ray tube displays. HITACHI Ltd. March 3, 1964 [April 3, 1963], No. 9033/64. Heading H4T. Signals (a1, Fig. 2) derived via a microphone A1 (Fig. 1, not shown), held in the region of the trachea and equalized in a circuit A2 (waveform a2) are displayed on the screen of a cathode-ray tube D against a time base which is triggered at a predetermined instant by a pulse (c). The latter is produced by counting in a circuit C a selected number of the pulses of a train (b1) produced in circuit B1 and the timespacing of which is equal to the period of the cycles of waveform (a1). Additionally, a circuit B 2  is employed to convert pulse train (b1) into a pulse train (b2) having amplitude variations corresponding to the variations in timespacing of (b1), i.e. amplitude variations corresponding to variations in pitch (frequency) of waveform (a1) and such variations are also displayed on the tube, e.g. by employing a dual beam tube. The input to circuit B1 may be replaced by the output of a reference generator E producing frequency modulated waves for calibration purposes. The tube preferably has a long persistence to facilitate direct visions.

United States Patent 3,345,979 APPARATUS FOR OBSERVING "OCAL CORD WAVETanetoshi Miura, Tokyo, and Tsuneji Koshikawa, Tokorozawa-shi, Japan,assignors to Hitachi, Ltd., Chiyodaku, Tokyo, Japan, a corporation ofJapan Filed Mar. 3, 1964, Ser. No. 349,059 4 Claims. (Cl. 1282) Thisinvention relates to an apparatus for observing the Wave form and pitchfluctuation features of vocal cord waves.

Vocal cord waves have an important role in linguistic education, vocaltraining and medical diagnosis in which defective functioning ofvocalization is to be detected and an appropriate treatment for vocaldisorder is to be determined. In order to judge the functioning ofvocalization accurately it is particularly important to know the waveform and pitch fluctuation features of the vocal waves.

It is an object of the present invention to provide an apparatus forobserving quantitatively and objectively the wave form and. pitchfluctuation features of vocal waves and thereby provide significantinsights for the functioning of vocalization.

The present invention will now be described in detail with reference tothe accompanying drawings which illustrate an embodiment thereof and inwhich:

FIGURE 1 shows a block diagram of an apparatus embodying the presentinvention, and

FIGURES 2a to 20 show wave forms which are used to explain the operationof the apparatus illustrated in block diagram form in FIGURE 1.

Referring to FIGURE 1, numeral 1 represents a microphone for extractingbody wall vibrations at the trachea and for translating the vibrationsinto electrical waves. The microphone 1 which is of the type describedin an article entitled, On the Extraction of the Pitch Signal Using theBody Wall Vibration at the Throat of the Talker," by Toshikako Sugimotoand Shizuo Hiki appearing in the proceedings of the Fourth InternationalCongress of Acoustics held at Copenhagen on Aug. 2l-28, 1962, pages 1through 4paper number G26, is held pressed against the wall of'thetrachea at a predetermined location. An equalizing circuit 2 isconnected to the microphone 1 to compensate for loss characteristicsintroduced by the wall of the trachea to the vocal cord waves. Theselosses are approximated by a low pass filtering characteristic and arecompensated for by a filter built into equalizing circuit 2. Suitablefilters for this purpose are disclosed in the Electrical EngineersHandbook, published by John Wiley & Sons, Inc, fourth edition, fourthprinting, February 196-3 and appearing on pages 654, 6-55 thereof. Thebody wall vibrations at the trachea (having a wave form shown in FIGURE2a are extracted by the microphone 1 and transformed into a (wave formshown in FIGURE 2a are similar to the vocal cord waves by passingthrough the equalizing circuit 2.

A circuit 3 also is connected to the microphone 1 through a switch 8 toa timing pulse extracting circuit 3 which may be of the type describedin the paper entitled Extraction and Portrayal of Pitch of Speech Sounds0. O. Gruenz, Jr. and L. O. Schott appearing in volume 21, number of theJournal of the Acoustical Society of America, September 1949, pages 487through 495. The timing pulse extracting circuit 3 serves to extract aseries of timing pulses (shown in FIGURE 2b having a period which isequal to the fundamental period of the related vocal cord waves. A pitchfluctuation extracting circuit 4, which may be of the type described inthe periodical Electrical Communication a technical 3,345,979 PatentedOct. 10, 1967 journal published by the International Telephone andTelegraph Corporation-volume 23, number 2, published June 1946 andappearing on pages through 171 thereof. The pitch fluctuation extractingcircuit 4 is connected to the circuit 3 to transform successive lengthsof the period (time intervals between succeeding pulses) of said seriesof pulses into a series of varying pulses. The extracting circuit 4includes an amplifying or level shifting circuit for adjusting thevoltage value of the pulses about a median value. The output of theextracting circuit 4 is shown in FIGURE 211 A counting and selectingcircuit 5 also is connected to the output of the circuit 3 and countsthe output pulses of the circuit 3 in order to obtain an outputsynchronized with the arrival of a desired pulse in the series. Theoutput of the counting and selecting circuit 5, which may be of the typedescribed in an article entitled An Industrial Batching Counter by R. W.Brierley appearing in Electronic Engineering Magazine--April 1954issuepages 157 through 160, is represented by a wave form shown inFIGURE 20. The pitch fluctuation shown in FIG- URE Zb which is theoutput of the extracting circuit 4 and the vocal cord wave shown inFIGURE 2a appearing at the output of the equalizing circuit 2, aredisplayed on a cathode ray tube 6 with starting of the horrizontal sweepbeing triggered by the output pulse 5 of the counting and selectingcircuit C. The sweep time of the cathode ray tube 6 is adjusted todisplay the phenomenon desired to be observed Within a particular timerange according to the object of the investigation. Thus wave form andpitch lfluctuation features of the vocal cord vibrations can be observedvery accurately and quantitatively.

It is preferable to employ a cathode ray tube of long persistency tofacilitate direct vision. A reference signal generator 7 may beconnected, if required, to the circuit 3 by means of a switch 8producing a timed series of reference pulses in order to compare theobserved wave with the reference signal pulses.

Having described one embodiment of an apparatus for observing vocal cordwaves constructed in accordance with the invention, it is believedobvious that other modifications and variations of the invention arepossible in the light of the above teachings. It is therefore to beunderstood that changes may be made in the particular embodiment of theinvention described which are within the full intended scope of theinvention as defined by the appended claims.

What we claim is:

1. An apparatus for observing vocal cord waves comprising: microphonemeans for extracting electrical vocal cord waves including pitchfluctuation features of vocal cord vibrations from body wall vibrationsat the trachea, filter means operatively coupled to the output from saidmicrophone means for compensating for loss characteristics of the wallof the trachea to said vocal cord waves, and time base display meansoperatively coupled to the output from said filter means for displayingsaid vocal cord waves including the pitch fluctuation features on anexpanded time base scale for observation purposes.

2. An apparatus for observing vocal cord waves comprising: microphonemeans for extracting electrical vocal cord waves from body wall waves atthe trachea, filter means operatively coupled to the output from saidmicrophone means for compensating for loss characteristics of the wallof the trachea to said vocal cord waves, first pulse forming circuitmeans operatively coupled to the output of said filter means forextracting pulses having a period which is equal to the fundamentalperiod of said vocal cord waves, second pulse forming circuit meansoperatively coupled to the output from said first pulse forming circuitmeans for transforming successive lengths of period into successivevariable voltage pulses to extract pitch fiuctuation features, and timebase display means operatively coupled 'to the output of said filtermeans and said second pulse forming circuit means for displaying saidvocal cord waves including the pitch fluctuation features on an expandedtime base scale for observation purposes.

3. An apparatus for observing electrical vocal cord Waves according toclaim 2 further comprising third pulse forming circuit means operativelycoupled to the output from said first pulse forming circuit means forderiving a desired synchronizing pulse signal from the output thereofand means for supplying the synchronizing pulse signal. to the time basedisplay means for synchronizing the time base scan thereof.

References Cited UNITED STATES PATENTS 2,705,742 4/1955 Miller 17913,024,783 3/ 1962 Timcke l282 3,245,403 4/ 1966 Lieberman l282 RICHARDA. GAUDET, Primary Examiner.

SIMON BRODER, Examiner.

1. AN APPARATUS FOR OBSERVING VOCAL CORD WAVES COMPRISING: MICROPHONEMEANS FOR EXTRACTING ELECTRIAL VOCAL CORD WAVES INCLUDING PITCHFLUCTUATION FEATURES OF VOCAL CORD VIRBATIONS FROM BODY WALL VIBRATIONSAT THE TRACHEA, FILTER MEANS OPERATIVELY COUPLED TO THE OUTPUT FROM SAIDMICROPHONE MEANS FOR COMPENSATING FOR LOSS CHARACTERISTICS OF THE WALLOF THE TRACHEA TO SAID VOCAL CORD WAVES, AND TIME BASE DISPLAY MEANSOPERATIVELY COUPLED TO THE OUTPUT FROM SAID FILTER MEANS FOR DISPLAYINGSAID VOCAL CORD WAVES INCLUDING THE PITCH FLUCTUATION FEATURES ON ANEXPANDED TIME BASE SCALE FOR OBSERVATION PURPOSES.